The present invention relates to a composition. In particular, the present invention relates to a composition comprising a pigment and a compound which acts as a dispersant, and methods for making and using the composition.
Liquid compositions containing a pigment typically require a dispersant to maintain the stability of the dispersant in the liquid carrier. Dispersants of the prior art have included adipates such as such as dioctyl adipate (DOA) and phthalate plasticisers such as dioctyl phthalate (DOP). The safety of these plasticisers has been called into question, particularly in certain applications and there is a desire to avoid their use.
Particular areas in which pigment dispersants have been used is in the provision of colourants for plastics, printing inks, and paints and lacquers.
As discussed in U.S. Pat. No. 5,308,395, traditionally, plastics have been coloured by tumble blending the plastic with a solid colourant or additive concentrate such as a colouring powder. The blended material is then fed into an extruder or moulding machine where the resin and the colourant are plasticised and the colourant is incorporated into the molten plastic. However, this method has a number of drawbacks. In many cases, a solid colourant or additive concentrate does not uniformly mix with plastic, or it does not disperse uniformly during moulding. Further, solid colourants often segregate from the plastic during pre-moulding handling because of particle size or specific gravity differences.
In recent years, liquid colour compositions have been developed in an effort to overcome the disadvantages of the traditional solid colourants. Being liquids, these colourant concentrates may be accurately metered directly into moulding machines or extruders by in-line metering systems, which help overcome many of the disadvantages of solid colourants.
As discussed in U.S. Pat. No. 5,531,819 printing inks are commonly used in ink jet printing systems. There have been proposed various kinds of ink jet recording systems, for example, a so-called electric field control system of jetting out ink by utilising an electrostatic attraction force; a so-called drop-on-demand system of jetting out ink by utilising a vibrational pressure of a piezo element (pressure pulse system); and a so-called thermal ink jet system of jetting out ink by utilising a pressure resulting from forming and growing bubbles by heating at high temperatures, and they can provide images of extremely high resolution.
For many ink jet systems, an aqueous ink using water as a main solvent and an oil ink using an organic solvent as a main solvent have generally been used. Printed images obtained by using the aqueous ink are generally poor in water proofing, whereas the oil ink can provide printed images of excellent waterproofing. U.S. Pat. No. 5,531,819 proposes plasticisers which may be used in oil inks.
As discussed in U.S. Pat. No. 4,230,609 pigments may also be delivered in the form of water reducible coatings. A water reducible coating is defined to be a colloidal dispersion in an organic solvent and water whose resin concentration can be reduced with water or solvent, which when reduced with a coalescing solvent forms a durable coating when applied to a substrate surface. Other names applied to water reducible coatings are water-borne, water solubilised, and water dilutable.
In a first aspect the present invention provides a composition comprising i) a pigment ii) a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 5 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of a chain having 10 to 20 carbon atoms and a hydrophilic branch group.
The dispersant of the present invention is (i) cost effective as it may synthesised from readily available products, for example castor oil, (ii) produces a stable dispersion with a wide variety of organic and inorganic pigments and dyes, (iii) allows for high pigment loads, and/or (iv) possess good shelf stability and uniformity.
In one aspect the composition of the invention is a pigment composition for colouring a polymer. In this aspect further advantages are observed.
The dispersant is compatible with a wide variety of commercial thermoplastic resins, is suitable for use in conventional in-line metering and blending equipment, produces uniform colour finished products without visible streaks or specks, eliminates screw slippage and/or is stable at the temperatures normally encountered in plastics moulding and extrusion equipment.
In one aspect the composition of the invention is a pigment composition for an ink. In this aspect further advantages are observed. The composition of the invention allows the provision of a hot melt ink, which is optimum as an ink for hot melt type ink jet recording, capable of reducing the heat of fusion without increasing the viscosity of the ink as a whole, improving transparency, providing plasticity, reducing haze (representing the extent of cloud, also referred as cloudiness), providing luster and/or easily dissolving a dye as a colorant and capable of providing a sufficient solubility, particularly to a black or cyanine dye.
In one aspect the composition of the invention is, or is usable in, a water reducible coating. In this aspect further advantages are observed. The composition of the invention may (i) provide for lower solvent cost; (ii) lower the amount of organic solvent used to decrease atmospheric pollution; (iii) lower phase inversion viscosityxe2x80x94the point at which the organic solvent (to which mixture water is being added) changes from a water-in-oil dispersion to an oil-in-water dispersion. This would make mixing easier and would require less energy to make up the composition; (iv) increase the solids content of the composition, to give coatings offering improved protection to substrate surfaces, without at the same time thickening the material and making it difficult to apply; (v) act as a plasticiser and therefore allow for a decrease in the addition of further plasticiser which in some applications may be detrimental to the coating, being extractable from the coatings by solvents; (vi) decrease carboxyl group content of the resin to decrease further the water sensitivity of the final coating.
In one aspect, the present invention provides a composition as herein defined in a medium.
Dispersant
In the present specification by the term dispersant it is meant that the compound may assist in the dispersion of a pigment in a medium. The medium may be for example a carrier, a solvent or a solid such as a polymer.
Preferably two of R1, R2 and R3 are short acyl groups as described above and the other of R1, R2 and R3 is a long acyl group as described above. In this aspect, the compound may be of the formula 
Preferably the hydrophilic branch group is a group selected from acyl and derivatives thereof. Preferred derivatives include groups of the formula xe2x80x94Oxe2x80x94acyl.
Preferably the hydrophilic branch group is a group of the formula 
wherein p is from 0 to 3.
In a preferred aspect of the present invention the chain of the long acyl group consists of a chain having 14 to 20 carbon atoms. In a more preferred aspect, the chain of the long acyl group consists of a chain having 16 to 20 carbon atoms.
Preferably the long acyl group is of the formula 
wherein n is from 10 to 20 and m is selected from 2n, 2n-2, 2n-4 and 2n-6, and wherein p is from 0 to 3.
Preferably n is from 16 to 20, more preferably from 16 to 18, yet more preferably 17.
Preferably m is 2n or 2n-2.
Preferably the group CnHm is a straight chain hydrocarbon group. The straight chain hydrocarbon group may be saturated or unsaturated. In one aspect, the straight chain hydrocarbon group contains a single xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
In a highly preferred aspect the long acyl group is a group of the formula 
wherein x is from 7 to 10, preferably x is 10, and y is 2x or 2x-2, and wherein p is from 0 to 3, preferably p is 0.
Preferably the group CxHy is a straight chain hydrocarbon group. The straight chain hydrocarbon group may be saturated or unsaturated. In one aspect, the straight chain hydrocarbon group contains a single xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
In a highly preferred aspect the long acyl group is a group of the formula 
In a preferred aspect of the present invention the short acyl group is an acyl group having from 2 to 5 carbon atoms. In a more preferred aspect, the short acyl group is an acyl group having 2 carbon atoms. The short acyl group is preferably of the formula 
Preferably the short acyl group and the hydrophilic branch group contain the same number of carbon atoms. In a highly preferred aspect the hydrophilic branch group of the formula 
and the short acyl group is the formula 
wherein p=q and is from 0 to 4 or 0 to 3.
In certain aspects, it is desirable for the short acyl groups to be present in a maximum amount with respect to the total amount of glycerol and esters thereof present in the composition. Preferably the short acyl group is present in an amount, on average, of no greater than 2 moles per mole of glycerol and esters thereof present in the composition.
In certain aspects, it is desirable for the long acyl groups to be present in a minimum amount with respect to the total amount of glycerol and esters thereof present in the composition. Preferably the long acyl group is present in an amount, on average, of at least 0.4 moles, preferably from 0.9 to 2 moles, more preferably from 0.9 to 1 moles per mole of glycerol and esters thereof present in the composition.
It may also be preferred for the majority of the glycerol present in the composition to be fully acylated. Accordingly, in a preferred aspect the total amount of acyl groups is, on average, 2.7 to 3.0 moles per mole of glycerol and esters thereof.
In a highly preferred aspect the compound of the present invention is selected from compounds of the formula 
The present invention further provides a composition comprising a pigment and a compound of the formula 
wherein two of R4, R5, and R6 are of the formula 
wherein for each of the two of R4, R5, and R6 q is independently selected from 0 to 3 and the other of R4, R5, and R6 is a branched group of the formula 
wherein n is from 10 to 20 and m is selected from 2n, 2n-2, 2n-4 and 2n-6, and wherein p is from 0 to 3.
Preferably q is 0. More preferably for both of the two of R4, R5, and R6 q is 0.
Preferably n is from 16 to 20, more preferably from 16 to 18, yet more preferably 17.
Preferably m is 2n or 2n-2.
Preferably the group CnHm is a straight chain hydrocarbon group. The straight chain hydrocarbon group may be saturated or unsaturated. In one aspect the straight chain hydrocarbon group contains a single xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
In a preferred aspect the branched group is a group of the formula 
wherein x is from 7 to 10, preferably x is 10, and y is 2x or 2x-2, and wherein p is from 0 to 3, preferably p is 0.
Preferably the group CxHy is a straight chain hydrocarbon group. The straight chain hydrocarbon group may be saturated or unsaturated. In one aspect, the straight chain hydrocarbon group contains a single xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
In one aspect, the present invention provides a pigment dispersing compound comprising a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 5 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of a chain having 10 to 20 carbon atoms and a hydrophilic branch group.
In this aspect, preferably the present invention provides a pigment dispersing compound comprising a compound as herein defined.
Method and Kit
In one aspect, the present invention provides a method for preparing a composition as herein defined, the method comprising admixing or contacting i) a pigment ii) a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 5 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of a chain having 10 to 20 carbon atoms and a hydrophilic branch group.
In one aspect, the present invention provides a method for dispersing a pigment or for improving pigment dispersing, the method comprising admixing or contacting the pigment with a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 5 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of a chain having 10 to 20 carbon atoms and a hydrophilic branch group; optionally in a medium.
In one aspect, the present invention provides a kit for preparing a composition as herein defined, the kit comprising i) a pigment ii) a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 5 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of a chain having 10 to 20 carbon atoms and a hydrophilic branch group; in separate packages or containers; optionally with instructions for admixture and/or contacting and/or use.
In a preferred aspect, the kit further includes a medium, wherein the medium can be included with the pigment, or with the compound, or with both the pigment and the compound, or in a separate package or container.
Process for Dispersant Preparation
The compound of the present invention may be prepared by interesterification between glycerol and one or more oils, including natural oils and hardened natural oils followed by acylation. Processes for the production of compounds in accordance with the present invention are disclosed in WO 01/14466. For example, the compound of the present invention may be the product of a two part process comprising (i) an interesterification between glycerol and an oil selected from castor oil, including hardened castor oil, unhardened castor oil and mixtures thereof, and (ii) acylation.
For example the compound may be prepared from castor oil or hardened castor oil. A typical fatty acid profile of castor oil and hardened castor oil is given below.
The nomenclature in parenthesis is Cxx:y where xx is the fatty acid carbon number and y indicates number of double bonds. Ricinoleic acid and hydroxystearic acid (also known as ricinoleic acid, hard) each have a hydroxyl group (OH) on the 12th carbon.
Pigment
The term xe2x80x9cpigmentxe2x80x9d when used herein denotes any conventional inorganic or organic pigment, dyestuff in particular organic dyestuffs, or carbon black. Those skilled in the art will be aware of suitable inorganic pigments, organic pigments and dyestuffs useful as colourants. Such materials are described, for example, in Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition, Vol. 6, pages 597-617, which is incorporated by reference herein. The pigment of the compositions of the present invention may be or comprise (1) inorganic types such as titanium dioxide, carbon black, iron oxide, zinc chromate, cadmium sulfides, chromium oxides, sodium aluminium silicate complexes, such as ultramarine pigments, metal flakes and the like; and (2) organic types such as azo and diazo pigments, phthalocyanines, quinacridone pigments, perylene pigments, isoindolinone, anthraquinones, thioindi-go, solvent dyes and the like.
Various conventional additives or mixtures thereof may also be included in the compositions of the invention such as, for example, lubricants, antistats, impact modifiers, antimicrobials, light stabilisers, filler/reinforcing materials (e.g., CaCO3), heat stabilisers, re-lease agents, rheological control agents such as clay, etc.
In a preferred aspect the pigment is or comprises a blend of a pigment, preferably a pigment as defined above, and a second pigment.
Coloured Systems
Polymer Systems
The compositions of the present invention may be used to colour or incorporate additives into a wide variety of polymeric resins and find equal application in modification of both thermoplastic and thermoset resins. For example, the colour concentrates of the invention are generally compatible with, and may be used with the following resins: polyolefins such as LLDPE, HDPE, LDPE, homopolymer and copolymer polypropylenes, EVA, etc.; styrenics such as crystal polystyrene, HIPS, MIPS, etc.; copolymer resins, resin blends and alloys such as ABS, polyphenylene ether (including PPO blends such as NORYLRTM(copyright)(trademark)), various engineering polymer alloys; polyamide resins, such as Nylon 6, 6/6, 11, 12, copolymers, terpolymers, etc.; acrylic resins, polycarbonates, and other amorphous resins; polyesters, such as PET, PBT, and othersxe2x80x94both thermoplastic and curing, as well as resins reinforced with glass, quartz, carbon, aramid, or the like, fibres.
Preparation of the composition of the invention can be by any of a number of methods known in the art including those set forth in Patton, Paint Flow and Pigment Dispersion, John Wiley and Sons (1979) and Weber, ed., colouring of Plastics, SPE Monographs, John Wiley and Sons (1979) which are incorporated by reference herein.
The composition of the invention may be added to a polymeric resin to be coloured in amounts up to about 10%, for example up to about 5%, based on the weight of the resin. The amount used is often referred to as the xe2x80x9cletdownxe2x80x9d or xe2x80x9cletdown ratioxe2x80x9d and is normally dependent on the colour intensity desired or required level of additive. Also, admixtures of one or more compositions may be employed to vary the colour or other properties of the resin.
A polymeric resin may be coloured by the composition of the present invention by intimate mixing. xe2x80x9cIntimatexe2x80x9d mixing means that the mixture is prepared with sufficient mechanical shear and thermal energy to produce a dispersed phase which is finely divided and homogeneously dispersed in the continuous or principal phase. For example, a particularly useful procedure is to intimately mix the polymeric resin with one or more compositions using conventional mixing equipment such as a mill, a Banbury mixer, a Brabender torque rheometer, a single or twin screw extruder, continuous mixers, kneaders, etc. The polymers may be intimately mixed in the form of granules, pellets, and/or powder in a high shear mixer. One preferred process for colouring polymeric resins according to the invention utilises an in-line metering system for direct incorporation of the composition into a polymer resin at the extruder or moulding machine. The composition may be added in measured amounts to the polymeric resin either by tumbling with the resin or by pumping the composition into the feed throat of a plastic machine or preferably metering into the polymer""s melt stream.
Ink Systems
As the colorant used for the ink of the present invention, any known dyes and pigments used in ink compositions may be used, for example.
As the pigment, either organic pigment or inorganic pigments used generally in the field of the printing technology can be used. Specifically, the following known pigments can be used with no particular restriction, for example, carbon black, cadmium red, molybdenum red, chromium yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, titanium cobalt green, ultramarine blue, prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinocridone pigment, isoindolinone pigment, dioxazine pigment, threne pigment, perylene pigment, perinone pigment, thioindigo pigment, quinophthalone pigment and metal complex pigment.
As the dye, oil-soluble dyes, for example, azo dye, disazo dye, metal complex dye, naphthol dye, anthraquinone dye, indigo dye, carbonium dye, quinone imine dye, cyanine dye, quinoline dye, nitro dye, nitroso dye, benzoquinone dye, naphthoquinone dye, xanthene dye, phthalocyanine dye and metal phthalocyanine dye are preferred, but not required.
The dye and the pigment may be used alone or in combination and contained within a range from about 0.1 to about 10% by weight, preferably, about 0.5 to about 8% by weight, and, more preferably, from about 0.7 to about 5% by weight based on the entire ink.
The compound of the present invention, which aids water resistance and abrasion resistance of the image printed with the printing ink of this invention, can be employed in an amount within the range of 0.1-10% by weight of the resin content, such as 2-10% by weight, and preferably about 4-6% by weight of the resin.
Paint/Lacquer Systems
The paint/lacquer systems of the present invention may comprise one or more of
Resinxe2x80x94a resin comprising units selected from
1. at least one hard hydrophobic enhancing monomer selected from styrene, .alpha.-methyl styrene, acrylonitrile, vinyl toluene, methyl methacrylate, vinyl chloride and vinylidene chloride;
2. at least one soft hydrophobic enhancing monomer selected from at least one acrylate selected from methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isodecyl methacrylate, butyl methacrylate, isobutyl methacrylate, at least one vinyl ether selected from ethyl, butyl, octyl, decyl, and cetyl vinyl ether and/or at least one diene selected from 1,3-butadiene, isoprene and 2,3-dimethyl butadiene, provided that said dienes of monomer part (2) are not mixed together and copolymerized with vinyl chloride or vinylidene chloride; and
3. at least one hydrophilic enhancing organic acid selected from acrylic, methacrylic, fumaric, itaconic and maleic acid;
The resins can be produced by reaction of the monomers in an aqueous emulsion medium. The principles of emulsion polymerization are discussed in the following references: Synthetic Rubber, WHITBY G. S., ed., John Wiley and Sons, 1954, Ch. 8; Emulsion Polymerization, Bovey F. A. et. al., Vol. IX of High Polymers, Interscience Publishers, Inc., 1955; and U.S. Pat. No. 3,714,122, col. 5, lines 41-67 and col. 6, lines 11-59.
A water soluble solventxe2x80x94selected from ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol diethyl ether, ethylene glycol monomethyl ether acetate, dipropylene-glycol methyl ether, methyl ethyl ketone, propylene glycol ethyl ether, propylene glycol isopropyl ether, propylene glycol butyl ether, acetone, methyl propyl ketone and diacetone alcohol;
A plasticiserxe2x80x94having a melting point of about xe2x88x9240xc2x0 C. to about 25xc2x0 C., a boiling point of at least 95xc2x0 C. and a solubility parameter of about 8 to about 16;
A volatile aminexe2x80x94in sufficient amount to result in a pH of from 8 to 14 for the composition;
Waterxe2x80x94in a volume ratio to the other volatile components of at least 80:20;
Of the various water soluble solvents which can be used, generally the ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether are preferred.
Representative of the various volatile amines which may be used to form the water reducible compositions are: primary amines such as ethyl amine, propyl amine, butyl amine, isoamyl amine, amyl amine, hexyl amine, heptyl amine and ethanol amine; secondary amines such as diethyl amine, ethyl ethanol amine, and morpholine; and tertiary amines such as dimethylethanol amine, trimethyl amine, triethylamine and N-methyl morpholine. Sufficient amine is added to achieve a pH in the final water dispersion of from about 8 to about 14, preferably 9.0 to 10.0.
The water insoluble solvent is generally selected from the group consisting of mineral spirits, ketones (e.g. methyl isobutyl ketone, MIBK), aromatic cycloparaffins, esters and acetates. It is either a true solvent for the resin or forms a true solvent for the resin when it is mixed with the water soluble solvent.
The invention will now be described in further detail in the following Examples.